textproduct: Albany

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1) Moderate confidence for slippery travel during the Tuesday afternoon commute due to an initial period of snow that changes to rain or a wintry mix of sleet and freezing rain with the greatest potential for a wintry mix in the northern/eastern Catskills, western New England, and the southern Adirondacks. There remains uncertainty regarding the areal coverage of wintry mix.

2) Moderate confidence for temperatures to trend warmer than normal for the end of the week into next weekend, especially in valley areas, which will likely ripen and partially melt the existing snow pack. With multiple opportunities for precipitation during this period, the combination of falling rain plus melting snow may start to break-up some existing river ice.

DISCUSSION

KEY MESSAGE 1...

Large scale high pressure and subsidence dominates that Northeast through Monday night and slowly exits off the New England coast. While zonal flow continues into Tuesday morning, warm air and moisture advection begins to increase as a weak shortwave and warm front lift northward. With a chilly antecedent air mass in place, initial precipitation should fall as mainly wet snow across eastern NY and western New England from south to north Tuesday morning into the afternoon. Upslope enhancements in the southern Adirondacks and southern Greens will likely allow snow to turn steady/moderate for a period. As enough warming occurs from south to north Tuesday afternoon, wet snow should mix with/turn to plain rain from the mid-Hudson Valley into the Greater Capital District with colder sfc temperatures in the Litchfield Hills, parts of western MA, northern/eastern Catskills and the Mohawk Valley supporting a changeover to a wintry mix including sleet and freezing rain. The combination of wet snow changing to rain and/or a wintry mix has increased concerns for slippery travel conditions Tuesday afternoon including the P.M commute so allow extra time if you plan to be on the road.

Temperatures continue to trend warmer Tuesday evening in response to continued warm air advection so coverage of wintry mix should diminish for areas south of I-90 but sfc temperatures look to struggle to warm in the southern Adirondacks, southern Greens and Upper Hudson Valley so snow and wintry mix likely lingering into Tuesday night, supporting continued slippery travel conditions. The main area of forcing exits to our east after 06 UTC Wednesday, allowing precipitation to diminish from west to east. Depending on how quickly the mid-levels dry out, some freezing rain may linger in the high terrain areas through early Wednesday morning but any freezing rain would be light/patchy.

Overall, storm total snow/sleet amounts range from 0.5 to 2.5 inches with the highest amounts north of I-90 where snow lingers the longest and upslope enhancements will increase snowfall rates. Latest probabilistic guidance from the NBM places the highest probabilities for 2 inches of snow or more north of I-90 but even these values only range 20 to 30%; therefore, there is increasing confidence that this will be a minor event which match with the latest WSSI-P values for minor impacts ranging 20 to 40%. Probabilities for moderate impact are virtually 0%. However, with pockets of freezing rain in the forecast in parts of western New England, the southern Adirondacks, Upper Hudson Vally, Mohawk Valley, and northern/eastern Catskills, winter weather advisories may still be needed to help message slippery travel from a glaze to 0.10" of flat ice.

KEY MESSAGE 2...

Moderate confidence continues for slightly above normal temperatures Wednesday through Friday with lower confidence for areas north of I-90 where, as discussed in the previous discussion, high pressure from Ontario looks to suppress the warmer air southward. However, there is moderate to high confidence for above normal temperatures this weekend regionwide as large scale ridging and southwesterly flow develops across the eastern CONUS.

Latest probabilistic guidance from the NBM shows a 60 to 80% for high temperatures on Wednesday to reach or exceed 45 degrees as high pressure and westerly flow returns to eastern NY and western New England. A warm front and associated sfc low then lifts northeastward out of the Midwest Thursday into Friday into the Northeast which reduces probabilities for warmer temperatures with the potential for 45F + temperatures only ranging 30 to 60%. Probabilities are lowest in the southern Adirondacks, the Upper Hudson Valley, and southern VT capped at 20 to 25% which look to remain mainly north of the incoming warm front. Depending on sfc temperatures, cannot rule out some wintry mix in these areas Thursday or Friday with plain rain expected elsewhere. Latest probabilities from the NBM show 50 to 70% chance for at least 0.75 inches of precipitation from 7AM Wed to 7AM Friday.

By the weekend, there is increasing confidence that southwesterly flow develops across the eastern CONUS, ushering in a much warmer air mass. In fact, latest probabilities from the NBM show at least 75% chance for temperatures to reach or exceed 45 degrees nearly regionwide both Saturday and Sunday. Probabilities are lowest in the southern Adirondacks and southern Greens closer to 60 to 75%. After this warm-up, a slow moving boundary looks to usher in multiple opportunities for widespread rainfall late this weekend into next week.

The prolonged period of warmer temperatures late this week through early next week should allow the existing snow pack ranging from 4 to 10" in valley areas to 2 to 3 feet in the southern Adirondacks and southern Greens to ripen and partially melt. Snow melt combined with rainfall from the upcoming active pattern could provide the necessary mechanisms to at least start breaking up existing ice on rivers, even in some northern and high terrain areas. Local research shows that break-up jams are more likely when the daily average temperature is at least 42 degrees and river levels rise at least 3 times the height of the ice thickness. We will continue to closely monitor temperature and precipitation trends for the end of this week into this weekend.

AVIATION /06Z MONDAY THROUGH FRIDAY/

Through 06z Tuesday...VFR conditions prevail across all terminals this morning amid clear skies under strong high pressure. Favored flying conditions are anticipated throughout the 06z TAF period as this high pressure remains in place. Some fair weather cumulus may develop later this afternoon, but generally skies remain mostly clear. Winds throughout the period will be light and variable at sustained speeds under 10 kt.

Outlook...

Tuesday Night: High Operational Impact. Definite RA. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: Moderate Operational Impact. Chance of SHRA...SHSN. Thursday: Moderate Operational Impact. Chance of RA. Thursday Night: High Operational Impact. Definite RA. Friday: Moderate Operational Impact. Chance of RA. Friday Night: Moderate Operational Impact. Chance of RA. Saturday: Moderate Operational Impact. Chance of RA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.